IntroductionAs in-house and in-cell recycling is developing (1-5) one should expect metal cleanliness issues to be of paramount importance. However, until now metal cleanliness has to some extent been a neglected aspect as low cost solutions and smart logistics often have received the main focus (6-9). The effect of inclusions on mechanical properties is pronounced and well-known in steels. Properties such as ductility, fatigue, toughness and machinablilty are affected (10-12). Also within the aluminium industry inclusions are of great concern (10). Molten magnesium alloys oxidise more readily than any other metal cast or formed into components used for construction purposes. One might expect this to trig primary producers, end-users as well as researchers interest in quantifying the impact of inclusions on important mechanical properties. However, to our knowledge only a few papers have been published addressing this topic featuring die cast magnesium alloys (13-15). The essence of these papers is that in order to detect any influence of inclusions the content must be really high (at least 0.2 %). This might have lead to the opinion that metal cleanliness represents no obstacle to go ahead with in-house/in-cell recycling.
Experimental
Test materialStandard die cast test bars were produced from AM50 melts deliberately contaminated with oxide inclusions. AM50 was chosen because this is a highly ductile magnesium based alloy, possibly making a reduction in tensile properties more easily visible than for instance with the less ductile AZ91. Molten metal cleanliness was adjusted in part by introducing thin-walled scrap to a reference ingot melt, and in part by turning off the gas protection for short periods allowing the melt to burn. It was not possible to predict the metal cleanliness, it could only be determined retrospectively. Molten metal cleanliness was monitored with the Hydro Magnesium Inclusion Assessment Method (HMIAM) (16,17), distinguishing between oxide particles and oxide films. Samples were withdrawn both before and after casting of the melts. The melts were stirred manually just before casting in order to interrupt the refining caused by settling. The chemical composition of the melts was controlled by spectrographic analysis of permanent mould cast specimens. Die casting of test bars was done on the 3-cavity test bar die on the 200 ton Frech machine in Hydro Magnesium's foundry laboratory. Standard die cast test bars were made from 17 Magnesium Alloys and their Applications. Edited by K. U. Kainer.
Two commercial Aluminium alloys with high Mn content were investigated in three different precipitation states. The rolling textures possess a portion of random orientations that is proportional to the volume fraction of larger particles. It is therefore identified with their deformation zones having about double the diameter of the particles. The recrystallization textures are weak for high annealing temperatures and show the more retained rolling texture the more the temperature is lowered. This is interpreted as a matter ofnucleation site.But also growth mechanisms influence the texture evolution. Minor texture components are characteristic for the different conditions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.